Which form of succession replaces
an
existing system after a calamity?

Secondary succession

Explanation:

Ecological succession is the term used to describe any series of change in the composition of an ecosystem over a particular period of time. Ecological succession is made up of two types viz: primary succession and secondary succession.

Primary succession involves the formation of a brand new ecosystem by the colonization of a barren area of land e.g bare rock, where no life existed. Secondary succession, on the other hand, is the recolonization of an area by a new set of organisms because the previously existing organisms have been wiped out by certain disasters e.g fire outbreak, hurricanes etc. In secondary succession, there is soil, which makes it possible for new organisms to sprout quickly after the calamity.

Example of secondary succession is when a fire outbreak burns the organisms in a community, allowing the root of grasses to sprout after.